How severe is GHSA-vp96-hxj8-p424?

No CVSS score has been assigned to GHSA-vp96-hxj8-p424 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-vp96-hxj8-p424?

GHSA-vp96-hxj8-p424 affects the following packages: pyopenssl (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-vp96-hxj8-p424?

Update pyopenssl to 26.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vp96-hxj8-p424 is resolved across your whole dependency graph.

How do I detect GHSA-vp96-hxj8-p424 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyopenssl, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-vp96-hxj8-p424 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is GHSA-vp96-hxj8-p424 actively exploited in the wild?

No public exploit code has been indexed for GHSA-vp96-hxj8-p424 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-vp96-hxj8-p424?

GHSA-vp96-hxj8-p424 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 17th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-vp96-hxj8-p424?

GHSA-vp96-hxj8-p424 is classified as CWE-636 (CWE-636). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-vp96-hxj8-p424 published, and has it been updated?

GHSA-vp96-hxj8-p424 was published on March 16, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callbackGHSA-vp96-hxj8-p424

Fix: pyca/pyopenssl@d41a814

GHSA-vp96-hxj8-p424 is a CWE-636 vulnerability in pyopenssl. A fix is available for pyopenssl — see the affected versions and patch details below.

Also known asCVE-2026-27448PYSEC-2026-2268

Published

Mar 16, 2026

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-vp96-hxj8-p424.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk+0.01%

Lower risk than most CVEs17th percentile — riskier than 17% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐍pyopenssl

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to set_tlsext_servername_callback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`pyopenssl`	≥ 0.14.0&&< 26.0.0	26.0.0`pip install --upgrade 'pyopenssl==26.0.0'`

Affected Products

1 product · 1 configurations

Application

pyopensslpyopenssl

≥ 0.14 && < 26.0.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyopenssl, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pyopenssl to 26.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vp96-hxj8-p424 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

This flaw is only exploitable when an application using the pyOpenSSL library provides a custom callback to the set_tlsext_servername_callback function. For the handshake to proceed incorrectly, the callback must raise an unhandled exception, limiting the exposure of this issue. Due to these reasons, this…

Workaround published by Red Hat

To mitigate this flaw, ensure the callback provided to the set_tlsext_servername_callback function is wrapped in a try/except block. This block should explicitly return a failure code instead of allowing the exception to propagate.

Source: Red Hat security advisory for GHSA-vp96-hxj8-p424 (CC BY 4.0)

Product	Fixed in	Advisory
Red Hat Hardened Images	`pyopenssl-main-26.0.0-1.1.hum1`	RHSA-2026:7224

Frequently Asked Questions

If a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Unhandled exceptions now result in rejecting the connection. Credit to **Leury Castillo** for reporting this issue.